Professor Snape does the high-pitched thing.
The last time Alan Rickman visited The Tonight Show set, Jimmy Fallon asked him if he's aware that many, many people impersonate him. The next night, Benedict Cumberbatch hung out with Fallon and the two participated in a glorious Rickman-Off.
This time, however, Rickman decided to chat about Harry Potter with Fallon while inhaling helium—which just sounds like the kinda thing Fallon would do, right? Yep. Watch below.